1. Field of the Invention
The present invention relates to a process for producing fuel by a catalytic cracking of vegetable oil that may be used in a pure state or mixed with fats and/or residual hydrocarbons from plastic pyrolysis by using ore-dolomite derived catalyst. This process transforms vegetable oils having high viscosity and heat content into high quality oil for fuel such as light and heavy naphtha, kerosene and diesel oil, in which glycerin is not produced as a byproduct in the transesterification process.
2. Description of the Related Art
Recently, the increasing price of crude oil, limited resource of fossil fuel (petroleum, coal and natural gas) and environmental concern lead to a new research where the use of alternative source and renewable energy such as biomass, solar, hydrogen and wind energy are being focused.
One of the most promising processes seems to be the conversion of vegetable oil, which primarily contains triglycerides and free fatty acid, to biodiesel because of its environmental benefit, for example low toxicity, biodegradability, lower sulfur content and finally limitation on greenhouse gas. Moreover, the well-known advantage is that the vegetable oil is one of the renewable resources.
Methyl or ethyl ester (biodiesel) is usually made from vegetable or animal oil via transesterification with alcohol in the presence of alkali as a catalyst. Methanol is commonly used for biodiesel production because of its availability and low cost. However, methanol is toxic and has a risk of fire. Biodiesel can be blended with petroleum diesel oil. It may, however, present somewhat of a drawback. The burning of methyl or ethyl ester of fatty acids generates formaldehyde and benzene, with deposit formation which causes damage to engines and pistons of engines. Thus, it is necessary to find a process to convert vegetable oil to high quality fuel oil which has a superior quality and physical characteristics that are very close to those of petroleum fuels.
Catalytic cracking process of vegetable oil for the production of fuel oil is one of the most promising methods because of its superior quality by having hydrocarbons which are mainly used for diesel oil.
U.S. Pat. No. 4,102,938 discloses a process for producing hydrocarbons from vegetable oils by thermolyzing them in the presence of a silica-alumina catalyst impregnated with any one of the oxides of the transition metals of groups IIB, IIIB, IVB, VB, VIB, VIIB and VIII of the Periodic Table at temperature ranging between 300° C. and 700° C. under atmospheric pressure in a fluidized bed, moving bed or fixed bed continuous tubular reactor, separating and purifying the resulting hydrocarbons.
However, there needs to be a great effort to combine a mixture of mineral hydrocarbon oil (petroleum kerosene of paraffin base) with vegetable oil through a process of hydrotreatment. US patent application publication No. 2007/0260102 discloses that the mixture flow is submitted to the process of hydrotreatment, obtaining as a result, a product flow with an elevated content of N-paraffins in the range of C10-C13.
The amount of plastic waste has been rapidly increasing every year which causes serious pollution problem. It requires landfill disposal, however, available landfill is limited. Thus, plastic waste is considered to be recycled by the thermo decomposition to obtain a petroleum resource. In view of lower capital cost, plastic waste is subjected to thermal cracking by a pyrolysis process to produce a heavy oil and then catalytic cracking to gasoline.
Some patents disclose that FCC catalyst is used in the catalytic cracking process of vegetable oil which is mixed with heavy or residual petroleum to produce diesel oil. For example, US patent application publication No. 2008/0313955 discloses a thermocatalytic cracking process for the production of diesel oil from a charge of vegetable origin made from seeds of oleaginous plants in refineries possesses at least two FCC reactors. At least one of such reactors processes heavy gas oil or residue under conventional conditions while at least one of such reactors processes the charge of vegetable origin made from seeds of oleaginous plants under conditions suitable, for production of diesel oil. Moreover, the diesel oil produced by the process has a cetane number over 40.
US patent application publication No. 2009/0026112 describes a fluid catalytic cracking process for the preparation of cracked products by contacting in a reactor a hydrocarbon feed stock with a cracking catalyst, wherein the hydrocarbon feedstock comprises a paraffinic feedstock and triglycerides.
U.S. Pat. No. 7,540,952 relates to a thermo catalytic process to produce diesel oil from vegetable oils, in refineries which have two or more catalytic cracking (FCC) reactors. This process employs the same catalyst employed in the FCC process, which processes conventional feedstocks simultaneously. At least one reactor processes heavy petroleum or residue in conventional operation conditions while at least one of such reactors processes the vegetable oil in proper operation conditions to produce diesel oil.
However, none of the above methods provides high quality oil for fuel with reasonable cost and with high efficiency.